Japanese Unexamined Patent Application Publication No. 11-113913 discloses an ultrasonic diagnostic apparatus which has a position detector at the edge thereof and easily obtains spatial ultrasonic image data along a route by advancing and returning a general radial scanning ultrasonic probe (including an ultrasonic endoscope with an optical observing window) along a bent or inflected luminal portion so as to obtain a plurality of ultrasonic tomographic images. Various expressing methods of the spatial ultrasonic image data are examined and Japanese Unexamined Patent Application Publication No. 11-113913 discloses the expressing method with an ultrasonic three-dimensional image or a plurality of cross-sectional images which are sectioned by planes in different directions.
Further, Japanese Unexamined Patent Application Publication Nos. 11-318884 and 2000-242766 disclose apparatuses which easily form cross-sectional images that are longitudinally sectioned by curved surfaces along an observation target such as the vein and the intestine from spatial image data and which display a guiding image indicating by which curved surface the cross-sectional image is longitudinally sectioned.
The apparatuses disclosed in Japanese Unexamined Patent Application Publication Nos. 11-318884 and 2000-243766 have view-point setting means in the observation target included in the original image, which display a tomographic image obtained by longitudinally sectioning the image by the curved surface passing through a plurality of view points.
However, in the apparatus disclosed in Japanese Unexamined Patent Application Publication No. 11-113913, the spatial ultrasonic image data is expressed as the tomographic image obtained by sectioning the image data by a certain plane and then, the luminal portion is expressed as piecemeal images as shown in FIG. 14 and the entire luminal portion is not displayed on the screen in many cases. Because the luminal portion in the living body does not run on the specific plane. FIG. 14 shows a state of the luminal portion which partly runs on the depth side from the cross section.
Consequently, the apparatus disclosed in Japanese Unexamined Patent Application Publication No. 11-113913 has the following problems.
First problem: it is hard to clarify how the lesion is spreading along the luminal portion.
Second problem: it is hard to clarify which part in the luminal portion is scanning during the examination.
In the apparatuses disclosed in Japanese Unexamined Patent Application Publication Nos. 11-318884 and 2000-243766, the view point upon drawing the curved surface is set after the examination, that is, after obtaining all the original images necessary for continuous viewing of the luminal portion.
Therefore, the first problem is solved after the examination. However, the apparatuses disclosed in Japanese Unexamined Patent Application Publication Nos. 11-318884 and 2000-243766 have a drawback that the first problem is not solved in real-time during the examination. Further, the apparatuses disclosed in Japanese Unexamined Patent Application Publication Nos. 11-318884 and 2000-243766 have a drawback that the second problem such that it is hard to clarify which part in the luminal portion is scanning during the examination (particularly, during the scanning) is still unsolved.
Incidentally, in the apparatuses disclosed in Japanese Unexamined Patent Application Publication Nos. 11-318884 and 2000-243766, it is not considered that the examination is performed by using an ultrasonic probe which is inserted in the luminal portion in the body cavity.
Upon using the radial scanning ultrasonic probe in the body cavity, generally, the following examining method is used. That is, in general, the lesion is found during the examination and an image thereof is recorded in view of the examination efficiency and the invasion to a subject and the ultrasonic probe is sooner removed as much as possible after approximate diagnosis.
However, in the apparatuses disclosed in Japanese Unexamined Patent Application Publication Nos. 11-318884 and 2000-243766, the first and second problems are not solved during the examination, therefore, the recording of the necessary image is not clearly recognized, and the advantage to easily express the tomographic image is not obtained.
The present invention is devised in consideration of the above-mentioned circumstances and it is an object of the present invention to provide an ultrasonic diagnostic apparatus which can recognize how the lesion is spreading along the luminal portion during the examination and which can easily recognize which part in the luminal portion is scanning during the examination by advancing and returning the radial scanning ultrasonic probe in the body cavity.